Cleaning agents are a large category, including inorganic cleaning agents and organic cleaning agents. The difference between organic cleaning agents and inorganic cleaning agents is very simple. Organic cleaning agents are made of carbon-containing compounds, while inorganic cleaning agents are made of carbon-free compounds, so they belong to inorganic substances.

Cleaning agents can be divided into industrial cleaning agents and civil cleaning agents according to their uses. It can be seen that there are two kinds of cleaning agents: liquid and solid.

Industrial cleaning agents include degreasing cleaning agents, wax cleaning agents, liquid crystal cleaning agents, cold stripping (normal temperature cleaning), rust removal cleaning agents, aluminate stripping and other varieties.

Civil cleaning agents include washing powder, hand sanitizer, soap, detergent and universal cleaning agent [1].

Cleaning agents can be divided into water-based cleaning agents and organic solvent cleaning agents according to different solvents.

Water-based cleaning agent means that the solvent is water, such as degreasing cleaning agent, detergent, washing powder, etc.

Organic solvent The cleaning agent solvent is organic solvent, such as trichloroethylene, acetone (nail water), natural water, boiling water, white oil, etc.

There are also many classification methods of cleaning agents, and the classification methods in different countries are different. We usually divide them into three categories: water-based cleaning agents, semi-water-based cleaning agents and non-water-based cleaning agents.

(1) water system

Water is the most important cleaning agent, which has irreplaceable function and status. Ordinary water is easily obtained from nature, and water has strong solubility and dispersibility. However, the surface tension of water is large, so it is necessary to add surfactants to reduce the surface tension and increase the surface wettability. In general industrial cleaning, the combination of acid, alkali and water is more common, and some metals need to be added with antirust agent when cleaning with water; Precision and ultra-precision industrial cleaning. Most require that water be made into pure water. The purity of water is usually measured by resistivity. The requirement of semiconductor industry is above 18mωcm. TN LCD can produce 10ω/cm, and some industries have strict requirements on bacterial content.

In recent years, some areas in China are seriously short of water, which poses a challenge to clean water. In some cities, it is forbidden to wash cars with ordinary water, and only recycled water or water-saving equipment with atomized water can be used. In precision industrial cleaning, it is expensive to prepare pure water. Water washing must be heated and dried, and many rinsing stations are added. Energy consumption is high, and the operating cost is usually higher than that of solvent washing; In addition, in the past, a large amount of wastewater containing chemical active agents and dirt was directly discharged without treatment. Some of them also contain toxic heavy metals, which seriously pollute the environment, so it is necessary to increase sewage treatment facilities.

(2) Semi-drainage system

Semi-water cleaning agent, also known as quasi-water cleaning agent, consists of high-boiling solvents and activators, such as alcohols, glycol esters, organic hydrocarbons, N- methylpyrrolidone and so on. They usually contain 5%-20% moisture and are generally not easy to burn.

However, improper water content control during heating and cleaning may lead to combustion. Semi-water cleaning is somewhat different from solvent cleaning. Its cleaning principle is peeling, not dissolving. In order to prevent the stripped oil from adhering to the object to be cleaned, the cleaning liquid should be continuously circulated, and the oil-water separator should be added. Semi-water cleaning usually has a good cleaning effect, but its running cost is high. The waste liquid cannot be recycled and contains high COD (chemical oxygen consumption).

(3) Non-water system

Non-aqueous cleaning agent refers to an organic solvent insoluble in water. Non-aqueous cleaning agents used in precision industrial cleaning mainly include hydrocarbons (petroleum), chlorinated hydrocarbons, fluorinated hydrocarbons, brominated hydrocarbons, alcohols, silicone oil, terpenes and other organic solvents.